Nitrogen inversion and N–O bond rotation in some hydroxylamine and isoxazolidine derivatives
作者:Azfar Hassan、Mohamed I. M. Wazeer、Herman P. Perzanowski、Sk. Asrof Ali
DOI:10.1039/a604719j
日期:——
A series of trisubstituted hydroxylamine derivatives, both cyclic and
acyclic, has been prepared. The energy barriers in these hydroxylamines
are found to be dominated either by nitrogen inversion or NâO
bond rotation depending on the nature of the substituents attached to
the nitrogen. In several series of compounds, having
XC6H4CH2 substituents attached to
nitrogen, Hammett free energy correlations are obtained with positive
Ï values, indicating increased electron density at the
transition state for the inversion process. Isoxazolidines with C(5)
ethoxy substituents demonstrate a strong anomeric effect.
一系列的三取代羟胺衍生物,包括环状和非环状,已被合成。这些羟胺中的能量障碍主要受到氮原子反转或N–O键旋转的影响,这取决于附着在氮原子上的取代基的性质。在几系列化合物中,氮原子上附有XC6H4CH2取代基,获得了哈梅特自由能相关性,并且ρ值为正,表明在反转过程的过渡态中电子密度增加。具有C(5)乙氧基取代基的异噁唑啉显示出强烈的异构效应。